Intraoperative Laryngeal Electromyography (LEMG) in

Children with Vocal Fold Immobility: A Longitudinal Study

LEMG Setup Guide

LEMG Setup Goal

• Capture EMG readings with audio from NIM and transfer to digital format that can be read by study neurologist

LEMG Setup

• Basic required equipment– Medtronic NIM Response 2.0 w/ VGA and

audio output– Video Converter (VGA to S-Video or

composite video)– Audio cable– Digital recording device (PC with video

recording software and CD/DVD burner)

LEMG Setup(What you need to buy…)

• Most ORs will need to buy a video converter– Any unit that will convert VGA output to S-video or

composite video will suffice• The current model of the unit used at MEEI is

available from:– Focus Enhancements Inc, Campbell, CA

(http://www.focusinfo.com/solutions/catalog.asp?id=151)

• TView Micro (part #:444-8600) $89 (requires USB port as power source)

Simplified LEMG Technique -MEEI Method

• Equipment– Medtronic NIM Response 2.0

• Must have VGA and audio output– Video converter (TView MicroXGA, Focus

Enhancements Inc, Campbell, CA)• Convert NIM output from VGA to S-video

or RCA to allow connection to digital video recorder

– Digital video recorder (Med X Change DRS2, Med X Change, Inc, Bradenton, FL)• Can use any PC with video input card, video

recording software and CD/DVD burner– Paired subdermal electrodes (Medtronic

PN#8227410)

ConnectionsNIM

Response 2.0 Unit

VGA Video Converter

Video Recorder / PC

VGA video cable

S-video or composite video cable

Audio cable

Produces CD/DVD

NIM interface box(small white box to plug leads into)

Paired subdermalleads

White NIM interface cable

Ground lead

NIM interface box connectionsPaired subdermal

electrodes (to patient’s larynx) Grounding lead

(to patient’s chest or

shoulder)

NIM interface cable

(to NIM machine)

NIM connections (without wires)

VGA Video Out

RCA Audio Out

NIM Connections(with wires in place)

VGA video cable

(to video converter)

RCA audio cable

(to video recorder)

Video converter connections

VGA video in

S-Video Out

Video converter connections(top view of the same)

VGA video in (from NIM)

S-Video out (to video recorder)

AC power in (from wall plug)

Video recorder / PC connectionS-Video in (from video converter)

RCA audio in (from NIM)

LEMG Setup

Preop NIM Setup

• Turn on machine– Quick setup screen

• Press “New”– This creates a new

profile

Preop NIM Setup

• Default screen appears

• Press “Left Vocalis” to assign lead 1 (blue)

Preop NIM Setup

• Press “Right Vocalis” to assign lead 2 (red)

• Press OK

Preop NIM Setup

• Type “LEMG”as setup name

• Press OK

Preop NIM Setup

• Press “Audio” to ensure audio is enabled

Preop NIM Setup

• Under “Tones”– ensure that “EMG

audio” and “Event Tones” are checked

• Then press “Display” to change amplitude settings

Preop NIM Setup

• Under “EMG Scales”– ensure that “Show

on main display” is checked

• Set amplitude to “50 µV”

• Set time to “50 mS”• Then press “Save”

Preop NIM Setup

• Press “LEMG” to get started

Preop NIM Setup

• Press “EMG” in top left corner to view EMG tracings started

Preop NIM Setup

• Ensure that time scale and amplitude are set at 50ms and 50 µV respectively

• Warning box will display until leads are placed

Intraop

• Place child into laryngeal suspension• Place subcutaneous grounding lead (green)

into chest/shoulder• Place electrodes into vocalis using alligator

forceps– Into belly of muscle without passing through

vocal fold– Blue into LEFT, Red into RIGHT

Intraop

Intraop

• EMG tracings are visible on NIM

Intraop

• Video recording on PC starts during emergence from anesthesia

• Electrodes are left in place until child is awake and tracings recorded– Gently pulled out at end of procedure

Special consideration

• If size of larynx or exposure precludes placing both leads simultaneously, may proceed with one side at a time. – Place lead and record during emergence

from anesthesia– Deepen anesthesia again and repeat on

the opposite side• Ensure that both recordings are

recorded and sent